<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 宽度weight 高度hight 背景色 back-ground -->
    <style>
        .red {
            width: 100px;
            height: 100px;
            background-color: brown;
        }

        .orange {
            width: 200px;
            height: 200px;
            background-color: orange;
        }
    </style>
</head>

<body>
    <div class="red">div1</div>
    <div class="orange">div2</div>
</body>

</html>